scholarly journals Feasibility Analysis of Magnetic Navigation for Vehicles

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5410
Author(s):  
Dongyan Wei ◽  
Lichen Huang ◽  
Xinchun Ji ◽  
Wen Li ◽  
Yi Lu ◽  
...  
Keyword(s):  
Satellite System ◽  
Statistical Characteristics ◽  
Distribution Model ◽  
Magnetic Navigation ◽  
Proposed Model ◽  
Positioning Technique ◽  
Global Navigation Satellite ◽  
The Magnetic Field ◽  
Comprehensive Indicator ◽  
Matching Window

Magnetic navigation is a promising positioning technique for scenarios where a global navigation satellite system (GNSS) is unavailable, such as for underwater submarines and aircraft in space. For ground scenarios, it faces more challenges, since the magnetic distribution suffers interference from surrounding objects such as buildings, bridges, and vehicles. It is natural to think how feasible it is to apply magnetic matching positioning to vehicles. In this paper, a theoretic distribution model is proposed to analyze the magnetic field around objects such as buildings, bridges, and vehicles. According to the experiments, it is shown that the proposed model matches the experimental data well. In addition, a comprehensive indicator metric is defined in this paper to describe the feasibility of the magnetic matching method based on the statistical characteristics of magnetic maps. The best length of matching window, anti-noise performance, and pre-comparison of positioning accuracy in different regions can be easily derived using the proposed comprehensive indicator metric. Finally, the metric is verified through a drive test using different building densities.

scholarly journals The Application of Robust Least Squares Method in Frequency Lock Loop Fusion for Global Navigation Satellite System Receivers

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1224 ◽  
Author(s):  
Mengyue Han ◽  
Qian Wang ◽  
Yuanlan Wen ◽  
Min He ◽  
Xiufeng He
Keyword(s):  
Least Squares ◽  
Least Squares Method ◽  
Satellite System ◽  
Complex Environment ◽  
Tracking Accuracy ◽  
Proposed Model ◽  
Robust Least Squares ◽  
Promising Application ◽  
Overall Performance ◽  
Global Navigation Satellite

The tracking accuracy of a traditional Frequency Lock Loop (FLL) decreases significantly in a complex environment, thus reducing the overall performance of a satellite receiver. In order to ensure high tracking accuracy of a receiver in a complex environment, this paper proposes a new tracking loop combining the vector FLL (VFLL) with a robust least squares method, which accurately matches the weights of received signals of different qualities to ensure high positioning accuracy. The weights of received signals are selected at the signal level, not at the observation level. In this paper, the ranges of strong and weak signals of the loop are determined according to the different expressions of the distribution function at different signal strengths, and the concept of loop segmentation is introduced. The segmentation results of the FLL are taken as a basis of the weight selection, and then combined with the Institute of Geodesy and Geophysics (IGGIII) weight function to obtain the equivalent weight matrix; the experiments are conducted to prove the advantages of the proposed method over the traditional methods. The experimental results show that the proposed VFLL tracking method has strong denoising capability under both normal- signal and harsh application environment conditions. Accordingly, the proposed model has a promising application perspective.

A distribution model of the GNSS code noise and multipath error considering both elevation angle and orbit type

2018 ◽  
Vol 233 (5) ◽  
pp. 1900-1915 ◽  
Author(s):  
Guochao Fan ◽  
Chengdong Xu ◽  
Jing Zhao ◽  
Xueen Zheng
Keyword(s):  
Prior Information ◽  
Elevation Angle ◽  
Satellite System ◽  
Distribution Model ◽  
Orbit Type ◽  
Integrity Monitoring ◽  
Multipath Error ◽  
Receiver Autonomous Integrity Monitoring ◽  
Orbit Types ◽  
Global Navigation Satellite

Commonly, the code noise and multipath error is considered to fully obey the Gaussian distribution. While in the cases with different elevation angles and orbit types, the assumption may be inappropriate. Based on an empirical study, by considering both the elevation angle and the orbit type, a new code noise and multipath distribution model is proposed to describe a more accurate code noise and multipath distribution in this paper. Actual code noise and multipath data from 10 observation stations during two months are researched, and the parameters and elevation angle range of code noise and multipath distribution model are determined. The code noise and multipath distribution model is verified to be more accurate than the model presented in the Global Navigation Satellite System Evolutionary Architecture Study report, according to the analysis on the code noise and multipath overbounding, position error overbounding, and the availability of receiver autonomous integrity monitoring. This model provides more accurate prior information for receiver autonomous integrity monitoring, especially its availability.

scholarly journals A Regional Zenith Tropospheric Delay (ZTD) Model Based on GPT3 and ANN

2021 ◽  
Vol 13 (5) ◽  
pp. 838
Author(s):  
Fei Yang ◽  
Jiming Guo ◽  
Chaoyang Zhang ◽  
Yitao Li ◽  
Jun Li
Keyword(s):  
Satellite System ◽  
Reference Station ◽  
Tropospheric Delay ◽  
Neutral Atmosphere ◽  
Zenith Tropospheric Delay ◽  
Satellite Positioning ◽  
Proposed Model ◽  
Radio Signals ◽  
Global Navigation Satellite ◽  
Gnss Data

The delays of radio signals transmitted by global navigation satellite system (GNSS) satellites and induced by neutral atmosphere, which are usually represented by zenith tropospheric delay (ZTD), are required as critical information both for GNSS positioning and navigation and GNSS meteorology. Establishing a stable and reliable ZTD model is one of the interests in GNSS research. In this study, we proposed a regional ZTD model that makes full use of the ZTD calculated from regional GNSS data and the corresponding ZTD estimated by global pressure and temperature 3 (GPT3) model, adopting the artificial neutral network (ANN) to construct the correlation between ZTD derived from GPT3 and GNSS observations. The experiments in Hong Kong using Satellite Positioning Reference Station Network (SatRet) were conducted and three statistical values, i.e., bias, root mean square error (RMSE), and compound relative error (CRE) were adopted for our comparisons. Numerical results showed that the proposed model outperformed the parameter ZTD model (Saastamoinen model) and the empirical ZTD model (GPT3 model), with an approximately 56%/52% and 52%/37% RMSE improvement in the internal and external accuracy verification, respectively. Moreover, the proposed method effectively improved the systematic deviation of GPT3 model and achieved better ZTD estimation in both rainy and rainless conditions.

Recovering authentic global position system L1 signals under spoofing using dual receiver direct positioning

2021 ◽  
pp. 1-19
Author(s):  
Chao Sun ◽  
Joon Wayn Cheong ◽  
Andrew G. Dempster ◽  
Hongbo Zhao ◽  
Wenquan Feng
Keyword(s):  
Thermal Noise ◽  
Single Channel ◽  
Satellite System ◽  
Statistical Characteristics ◽  
Reference Station ◽  
Spoofing Detection ◽  
Gnss Receivers ◽  
Position Solution ◽  
Global Navigation Satellite ◽  
Mathematical Derivation

Abstract Spoofing is a kind of deliberate interference that aims to manipulate global navigation satellite system (GNSS) receivers into counterfeit position solutions. Conventional anti-spoofing methods are implemented prior to the calculation of the position solution, depending on the specific spoofing attack mechanisms. The paper presents a spoofing detection and mitigation method implemented in the position domain. The proposed method projects the correlograms of the visible satellites to a position-clock bias domain to construct the position domain projected correlogram. P(Y) code signatures retrieved from a reference station receiver are used to identify the counterfeit position solution and remove it from the victim receiver. Compared with the conventional single-channel spoofing detection technique, the proposed anti-spoofing method is more robust against thermal noise by combining the energy from multiple satellites. Detailed mathematical derivation of the statistical characteristics of this method is presented. Its effectiveness is validated using a realistic dataset generated by a Spirent GNSS simulator and NordNav wideband front-end. Results show that the proposed algorithm is capable of not only detecting a spoofing attack but also removing the spoofing effect from the victim receiver.

scholarly journals Evaluation The Performance Geodetic of the Receivers Using Static Positioning Technique

2018 ◽  
Vol 24 (10) ◽  
pp. 98
Author(s):  
Omar Ali Ibrahim
Keyword(s):  
Satellite Communications ◽  
Satellite System ◽  
Web Based ◽  
Static Mode ◽  
Total Station ◽  
Land Surveying ◽  
Gnss Receivers ◽  
Positioning Technique ◽  
Mobile Satellite ◽  
Global Navigation Satellite

Global Navigation Satellite System (GNSS) is considered to be one of the most crucial tools for different applications, i.e. transportation, geographic information systems, mobile satellite communications, and others. Without a doubt, the GNSS has been widely employed for different scientific applications, such as land surveying, mapping, and precise monitoring for huge structures, etc. Thus, an intense competitive has appeared between companies which produce geodetic GNSS hardware devices to meet all the requirements of GNSS communities. This study aims to assess the performance of different GNSS receivers to provide reliable positions. In this study, three different receivers, which are produced by different manufacturers, were fixed to form a triangle. Simultaneous observations were made in static mode (2.5 to 3 hours). This observation technique was carried out three times by changing the location of receivers in each time to ensure that three receivers observed each station three times. To evaluate the performance of each receiver, OPUS web-based processing software and TOPCON TOOLS were used to process the raw GNSS observations. The distances between adjacent stations were computed for each observation and compared to standard distances, which were measured using a total station. Furthermore, the internal angles were also computed and compared to those measured by Total Stations. The results showed that some calculated distances are closer to the corresponding distances measured by the total station. This indicates that the receivers involved in the composition of these distances are the most accurate.  

Recurrent Neural Networks for Ionospheric Time Delays Prediction Using Global Navigation Satellite System Observables

2021 ◽  
Author(s):  
Maria Kaselimi ◽  
Nikolaos Doulamis ◽  
Demitris Delikaraoglou
Keyword(s):  
Global Navigation Satellite System ◽  
Satellite System ◽  
Electron Content ◽  
Navigation Satellite ◽  
Total Electron ◽  
Proposed Model ◽  
Model Complex ◽  
Global Navigation ◽  
Global Navigation Satellite

<p>Total Electron Content (TEC) is the integral of the location-dependent electron density along the signal path and is a crucial parameter that is often used to describe ionospheric variability, as it is strongly affected by solar activity. TEC is highly depended on local time, latitude, longitude, season, solar and geomagnetic conditions. The propagation of the signals from GNSS (Global Navigation Satellite System) throughout the ionosphere is strongly influenced by short- and long-term changes and ionospheric regular or irregular variations. <br>Long short-term memory network (LSTM) is a specific recurrent neural network architecture and is capable of learning time dependence in sequential problems and can successfully model ionosphere variability. As LSTM networks “memorize” long term correlations in a sequence, they can model complex sequences with various features, where solar radio flux at 10.7 cm and magnetic activity indices are taken into consideration to provide more accurate results. <br>Here, we propose a deep learning architecture to create regional TEC models around a station. The proposed model allows different solar and geomagnetic parameters to be inserted into the model as features. Our model has been evaluated under different solar and geomagnetic conditions. Also, the proposed model is tested for different time periods and seasonal variations and for varying geographic latitudes. </p>

Long-Term GNSS Analysis for Local Geodetic Datum After 2011 Tohoku Earthquake

2017 ◽  
Vol 71 (1) ◽  
pp. 117-133
Author(s):  
Su-Kyung Kim ◽  
Tae-Suk Bae
Keyword(s):  
Reference Frame ◽  
Tohoku Earthquake ◽  
Satellite System ◽  
2011 Tohoku Earthquake ◽  
The 2011 Tohoku Earthquake ◽  
Proposed Model ◽  
Global Navigation Satellite ◽  
Gnss Data ◽  
Geodetic Reference Frame

The current Korean national geodetic reference frame, KGD2002, refers to the fixed epoch at 2002·0 under the assumption that there is no crustal movement of the Korean peninsula. A discontinuity in the coordinates of the reference stations may occur due to the relocation of the stations, antenna replacement, or earthquakes. The static reference frame has difficulty in covering continuous and/or discontinuous crustal movements at the same time. A new dynamic local geodetic reference frame has been calculated based on eight years (2007–2014) of Global Navigation Satellite System (GNSS) data. The final geodetic coordinates and velocities were calculated on the basis of the IGb08 reference frame. The discontinuity caused by the 2011 Tohoku earthquake can be addressed using the newly proposed model in this study, which ensures the consistency and continuity of the local geodetic datum.

scholarly journals Positioning Using IRIDIUM Satellite Signals of Opportunity in Weak Signal Environment

Electronics ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 37 ◽  
Author(s):  
Zizhong Tan ◽  
Honglei Qin ◽  
Li Cong ◽  
Chao Zhao
Keyword(s):  
Estimation Algorithm ◽  
Satellite System ◽  
Positioning System ◽  
Weak Signal ◽  
Open Environment ◽  
Signal Characteristics ◽  
Signal Environment ◽  
Positioning Technique ◽  
Global Navigation Satellite ◽  
Signals Of Opportunity

In order to get rid of the dependence of the navigation and positioning system on the global navigation satellite system (GNSS), radio, television, satellite, and other signals of opportunity (SOPs) can be used to achieve receiver positioning. The space-based SOPs based on satellites offer better coverage and availability than ground-based SOPs. Based on the related research of Iridium SOPs positioning in the open environment, this paper mainly focuses on the occluded environment and studies the Iridium SOPs positioning technique in weak signal environment. A new quadratic square accumulating instantaneous Doppler estimation algorithm (QSA-IDE) is proposed after analysing the orbit and signal characteristics of the Iridium satellite. The new method can improve the ability of the Iridium weak signal Doppler estimation. The theoretical analysis and positioning results based on real signal data show that the positioning based on Iridium SOPs can be realized in a weak signal environment. The research broadens the applicable environment of the Iridium SOPs positioning, thereby improving the availability and continuity of its positioning.

scholarly journals INTEGRATION OF PDR AND IMAGE-BASED POSITIONING AIDED BY ARTIFICIAL NEURAL NETWORKS IN INDOOR ENVIRONMENT

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 181-185
Author(s):  
M. C. Hung ◽  
K. W. Chiang
Keyword(s):  
Dead Reckoning ◽  
Satellite System ◽  
Indoor Positioning ◽  
Indoor Navigation ◽  
Positioning Method ◽  
Pros And Cons ◽  
Positioning Technique ◽  
The Mean ◽  
Global Navigation Satellite ◽  
The Cost

Abstract. Location based service (LBS) is a popular issue in recent years, which can be applied widely. The most common one is providing the local information and the guide of the Point of Interesting (POI) to users, which means positioning is the necessary technique to put LBS into practice. In an outdoor scenario, the user’s position can be obtained relying on the Global Navigation Satellite System (GNSS), however, the signal of GNSS might be blocked in a building. So, many indoor positioning techniques are developed in the decades, which have the pros and cons respectively. This paper proposes an indoor positioning technique by integrating Pedestrian Dead Reckoning (PDR) with the image-based positioning method, which can decrease the cost significantly because it only needs a camera built-in the smartphone. In the first experiment, we verify the accuracy of positioning by the proposed method, that the mean error in the horizontal direction is about 0.25 meters. In the following experiment, comparing with the misclosure of PDR only and PDR integrated with the proposed method, it can decrease from 8.53% to 1.44%. The improvement is about 83%, therefore, this method is suitable for applying to indoor navigation.

scholarly journals Complexity and Limitations of GNSS Signal Reception in Highly Obstructed Enviroments

2021 ◽  
Vol 11 (2) ◽  
pp. 6864-6868
Author(s):  
A. Hussain ◽  
F. Akhtar ◽  
Z. H. Khand ◽  
A. Rajput ◽  
Z. Shaukat
Keyword(s):  
Signal Strength ◽  
Satellite System ◽  
Statistical Characteristics ◽  
Navigation Systems ◽  
Path Delay ◽  
Range Measurements ◽  
Signal Characteristics ◽  
Satellite Visibility ◽  
Nlos Reception ◽  
Global Navigation Satellite

Multipath (MP) and/or Non Line-Of-Sight (NLOS) reception remains a potential vulnerability to satellite-based positioning and navigation systems in high multipath environments, such as an urban canyon. In such an environment, satellite signals are reflected, scattered or faded, and sometimes completely blocked by roofs and walls of high-rise buildings, fly-over bridges, complex road structures, etc. making positioning and navigation information inaccurate, unreliable, and largely unavailable. The magnitude of the positioning error depends on the satellite visibility, geometric distribution of satellites in the sky, and received signal quality and characteristics. The quality of the received signal (i.e. its statistical characteristics) can significantly vary in different environments and these variations can reflect in signal strength or power, range measurements (i.e. path delay and phase difference), and frequency, all of which distort the correlation curve between the received signal and receiver-generated replicas, resulting in range errors of tens of meters. Therefore, in order to meet stringent requirements defined for the Standard Positioning Service (SPS), the characterization of distortions that could significantly affect a Global Navigation Satellite System (GNSS) signal is essentially important. The scope of this paper is to detect possible imperfections/deviations in the GNSS signal characteristics that can occur due to MP or NLOS reception and analyze its effects. For this purpose, analysis of fading patterns in received signal strength (i.e. Carrier-to-Noise Ratio and strength fluctuations) is carried out in both clear LOS and high MP environment and then its impact on satellite lock state (i.e. tracking) is assessed. Furthermore, phase fluctuations and range residuals are computed to analyze the effects of path delays. The results show that significant variations can occur in GNSS signal characteristics in the MP environment that may result in loss of lock event and inaccurate/faulty range measurements.

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